The invention relates to an instrument for applying vibrations to the human body.
It is already known that mechanical vibrations can exert a therapeutic action. For example, muscle tension can be released by means of vibrations.
The vibration instruments or vibration appliances available at the present time have a vibration head which is actuated via an electromagnetic drive device. The electromagnetic drive normally comprises a motor and an oscillator coil. The oscillations of the vibration head in these known appliances are generally periodic, and the frequency of the vibration, because of the direct mains supply of the electromagnetic drive, is 50-60 Hz, with the result that the leading edge of the vibration stroke of the vibration head is approximately 2.5 ms. The action exerted on body tissue by the vibration head of conventional vibration appliances of this kind is such that, when the vibration head is placed on the skin, cellular processes can be activated in the underlying tissue by the vibrations generated by the vibration head. However, the known vibration appliances have the disadvantage that, because of the electromagnetic drive, the vibrations are relatively slow, which in some cases reduces the therapeutic effect. Moreover, because of the electromagnetic drive, the conventional vibration appliances are also relatively heavy and therefore difficult to handle.
Pressure-wave and/or shock-wave instruments and appliances for therapeutic purposes are also known, for example from the document DE-C-197 25 477.
In contrast to vibration appliances, pressure-wave appliances generate very hard pressure waves or shock waves which have a leading edge of ca. 2 μs and an amplitude of ca. 15 MPa (measured at a distance of 1 cm from the applicator). These pressure-wave instruments or appliances have, at the distal end, an axially movable ram whose axial stroke, however, is very small, for example a maximum of 0.2 mm. To generate a pressure wave or shock wave by means of the ram, a drive device is provided which comprises an axially movable projectile, arranged proximally of the ram, and an accelerating device for the projectile. The accelerating device usually operates pneumatically with compressed air at approximately 2-4 bar. By means of the impact of the projectile accelerated by the accelerating device and striking the proximal end of the ram, a pressure wave or shock wave builds up in the ram, which wave runs from proximal to distal through the ram and there leaves the ram as pressure wave or shock wave and can penetrate into the body tissue. The ram generally has a much greater mass than the projectile and is held relatively rigidly in the housing of the instrument handpiece. As has already been mentioned, the travel of the ram in such pressure-wave appliances is very small as a result of the impact.
The therapeutic action of pressure waves or shock waves is different than that of mechanical vibrations, so that pressure-wave instruments or appliances of this kind are used for treatment of other clinical symptoms, for example the treatment of calcifications of the tendon insertions and such like.
Document U.S. Pat. No. 4,549,535 discloses a massage instrument comprising a ram and, proximally of the ram, a piston which can be accelerated in the direction of the ram by means of an electromagnetic linear drive.
Document U.S. Pat. No. 4,716,890 describes an instrument for use in chiropractic treatment, having an axially movable ram which is provided with a rubber tip and whose stroke length can be adjusted in order to adapt the force exerted on the body. The ram is triggered by means of a pneumatic drive mechanism, with compressed air acting on a spring-pretensioned piston which is accelerated distally by the compressed air in order to move the ram in the distal direction. The ram itself is not pretensioned in its proximal position.